Method of annealing metal



E. G. BUDD AND J. LEDWINKA.

METHOD OF ANNEALING METAL.

APPLICATION FILED SEPT. 6. I916.

Patented Aug. 29, 1922.

UNITED STATES PATENT OFFlfiE.

EDWARD G. BUIID AND JOSEPH LEDWINKA, OF PHILADELPHIA, PENNSYLVANIA,ASSIGNOBS '10 EDWARD G. BUDD MANUFACTURING COMPANY, OF PHILADELPHIA,PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA. 1

'HETHOD OF ANNEALING METAL.

Specification of Letters Patent. Patented Aug, 29, 1922,

Application filed September 6, 1916. Serial No. 118,715.

To all whom z't may concern:

Be it known that we, EDWARD G. Bonn and J osnrrr LEDWINKA, citizens ofthe United States, residing at Philadelphia, in the county ofPhiladelphia, State of Pennsylvania, have made a certain new and usefulInvention in Methods of Annealing Metal, of which the following is aspecification.

This invention relates to the method of annealing metals.

The object of the invention is to provide a simple, efficient,economical, and expeditious method of annealing metals.

A further object is to provide a method of the nature referred to whichis carried out electrically.

The invention consists substantially in the mode of operationhereinafter set forth, as illustrated in the accompanying drawing, andfinally pointed out in the appended claims.

In its broadest scope our invention contemplates subjecting the metal toan annealin heat while removed from the oxidizing .in uence of air,oxygen or other gases. In

a more particular specification of our invention we propose to vinclosethe material to be annealed-within an air tight chamber and then exhaustthe chamber of its air or other oxidizing gas, and then heat the metalelectrically to the required or desired annealing temperature, andfinally before removing the metal from the chamber permitting the sameto cool sufficiently so that it willnot be affected by or oxidized whenagain brought in contact with air.

The operation may be carried out in a vast variety of ways and by meansof different arrangements of apparatus. While, therefore, we have shown,and will describe various arrangements for carrying our invention intopractical operation, we, wish it to be understood that the arrangementsshown, are merely illustrative of the. principles involved.

Fig. 1 is a view in perspective, parts broken out and parts in section,showing one form of arrangement adapted for use in carrying out ourinvention.

Fig. 2' is a view in longitudinal section showing another arrangementsuitable for the purposes of our invention.

In accordance with our invention, and referring more particularly toFig. 1, the material to be annealed say, for example, a

metal sheet orplate 3, is placed within an air tight chamber 4, and issupported and suspended therein by means of clamps 5 connected to itsends. These clamps constitute electric circuit terminals so that themetal sheet or plate, in the example given, forms part of the electriccircuit which includes the terminal clamps 5.

Any oxidizing agent contained in the chamber is then removed. This maybe accomplished in any suitable or convenient manner, such, for example,as by exhausting said chamber of its air or other oxidizing agent, bymeans of the pump 6, or other equivalent means, or by supplying thechamher with some inert non-oxidizing agent, as from the supply tankindicated at 7, or the chamber may be exhausted of its air and the inertnon-oxidizing agent also supplied, the essentialfeature being theremoval of all, or substantially all, oxidizing influence from theclosed chamber and the space surrounding the metal to be annealedpreparatory to heating the metal.

In Fig. 2. we have shown means for producing a high tension electricspark or discharge, indicated at 8, within the chamber 4, as a means forexhausting said chamber of its oxidizin air,,the spark terminals 10, 10,being inclu led 1n circuit connections 11, 11, supplied with hightension current from any convenient source.

After the removal of the oxidizing a ent, air or gas, or the influencethereof, rom the air tight space surrounding the metal to be annealed,the metal is then heated to the desired annealing temperature. This maybe accomplished in any suitable or convenient manner. In practice wehave found it practicable and desirable to accomplish the heating of themetal electrically, and in one form of electric heating arrangementsuitable for the purpose we propose to employ a heating current of lowvoltage and big amperage. To this end the clamps 5, constitute theterminals of the secondary coil member 12 of a transformer, which coilis surrounded by the core 13 of the primary coil 14, the latter beingsupplied with electric current of high voltage and low amperage in'awell known manner. By suitably controlling the current supplied to theprimary coil 14 of the transformer a heatgas or ing current of thedesired character, capable of heating the metal to be annealed to thedesired annealing temperature according to the nature or character ofthe metal, sheet or plate under treatment, is induced in the secondarymember 12 of the transformer.

After the metal has been sufliciently heated to effect the'desiredannealing thereof, the current 'is shut off from the primary coil of thetransformer and the metal is permitted to cool sufficiently to beunaffected by the oxidizing action of the air, and the c amber is thenopened up, the annealed metal is removed, and replaced by a new piece tobe annealed, and the process repeated.

From the foregoing description it will be seen that after the metalsheet or plate is placed in the chamber 4, it is maintained in saidchamber throughout the heating and preliminary cooling operationswithout removal. This obviates the necessity of providing air tightgates or passages for the travel of the material to be annealed throughthe chamber as in the case of continuous annealing operations such ashave heretofore been proposed, and which are objectionable for thereason that passages to permit the material to travel through theannealing chamber are diflicult to maintain air tight particularly wherethe exhaustion of the chamber is carried to any substantial or effectivedegree, and any access of air or other oxidizing agent through leakageor other cause is detrimental to the annealing action. This trouble weentirely avoid in our process and apparatus wherein the material to beannealed is not only enclosed in the chamber but is maintained thereinwithout movement therethrough during the exhausting or non-oxidizing gassupply, the heating and the cooling operations.

The annealing process above described is effectively carried outexpeditiously, economically and satisfactorily. Uniformity of resultsare attained, and accurate regulation according to the size, characterand nature of the material is permitted.

Having now set forth the objects and nature of our invention, and themanner of carrying the same into practical operation, what We claim asnew and useful, and of our own invention, and desire to secure byLetters Patent is:'

1. The method of annealing metal which consists in enclosing the part tobe annealed and removing therefrom the oxi-e dizing effect of thesurrounding medium, and including the same in series in the secondarycircuit of an electrical transformer to heat the same to an annealingtem erature, and finally cooling such part be ore exposure thereof tooxidizing influences.

2. The method of annealing metal which consists in surrounding the partto be annealed with an inert non-oxidizing agent and connecting the samein series in the secondary circuit of an electrical transformer to heatthe same to an annealing heat, and then cooling such art before exposurethereof to oxidizing influences.

3. The method of annealing metal which consists in including the part tobe annealed in series in the secondar circuit of an electricaltransformer an removing therefrom oxidizing influences of thesurrounding medium while the same is heated to an annealing temperature,and then cooling the same before exposure to oxidizing influences.

4. In an apparatus for annealing metal, a closed chamber within whichthe part to be annealed is maintained and fixed, a transformer, thesecondary of said transformer having its terminals connectedrespectively to the ends of the part to be annealed, and means to removethe oxidizing influence of the medium contained in said chamber.

In testimony whereofwe have hereunto set our hands in the presence ofthe subscribing witnesses, on this 30th day of August A. D. 1916.

EDWARD G. BUDD. JOSEPH LEDWINKA.

Witnesses:

L. R. HILYARD, A. H. BUXBAUM.

